[ILUG] gcc and printf style functions

[Brian Foster]

  | Date: Fri, 4 Mar 2005 12:48:07 +0000
  | From: kevin lyda <kevin+dated+1110372506.52995e at ie.suberic.net>
  |[ ... ]
  |     int sqlite_exec_printf(sqlite *db,
  |                            char *sqlfmt,
  |                            int (*xCallback)(void*,int,char**,char**),
  |                            void *pArg,
  |                            char **errmsg,
  |                            ...)  __attribute__((format(printf, 2, 6)));

 tip:  unless you are doing something sneaky elsewhere,
      it is a good idea to use __format__ and __printf__,
      i.e.:  __attribute__((__format__(__printf__, 2, 6)))
      because those names are less likely to be #define'd
      by some idio^H^H^H^H^Hone else.

  |[ ... ]
  | i've read through the gcc docs and as far as i can see, i'd need to
  | change gcc in order to support new % format codes.  am i missing
  | something?

 I've always assumed --- but without research! --- that
 the % codes are hardwired into gcc.  in addition to
 the answer to Kevin's question, I would be interested
 in knowing:

   - is it possible, without changing gcc, to remove
     or redefine some of the % codes it does know?

   - if it is possible to add remove or change % codes,
     can that be concurrently used with the UN-altered
     definitions for "real" printf(3)?

   - does gcc know about the `m$' construction, as
     in `%3$d' to printf the 3rd argument as `%d'?

 it's never been too important, but if someone just
 happens to know ....  thanks.

cheers!
	-blf-
-- 
Experienced (20+ yrs) kernel/software Eng: | Brian Foster   Montpellier,
 • Unix, embedded, &tc;  • Linux;  • doc;  | blf at utvinternet.ie   FRANCE
 • IDL, automated testing, process, &tc.   |  Stop E$$o (ExxonMobile)!
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